SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '683782dfd6058be3a2c40f6c55adfb92b77a6474dbcec18acd29ee8df99a1e8a' 
  AND token = 'GguFn/wuWxSU/VUvupEWz6OtmbAQqsJ+lUhD54Ca1dI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}